Mask shell



FIG. 1 is a front, right side perspective view of a mask shell showing my new design, shown in a folded position;

FIG. 2 is a rear, left side perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a front view thereof;

FIG. 8 is a rear view thereof;

FIG. 9 is a front, right side perspective view thereof, shown in an extended position;

FIG. 10 is a rear, left side perspective view of FIG. 9;

FIG. 11 is a top view of FIG. 9;

FIG. 12 is a bottom view of FIG. 9;

FIG. 13 is a right side view of FIG. 9;

FIG. 14 is a left side view of FIG. 9;

FIG. 15 is a front view of FIG. 9; and,

FIG. 16 is a rear view of FIG. 9. 

CLAIM The ornamental design for a mask shell, as shown and described. 